Devices for the processing, in particular also for the transverse cutting, of highly diverse objects are known from a number of production processes. Reference is made to WO 01/28865 A1 in this regard. The transverse cutting of moving, relatively flat cheese bands is also known, in particular. In this regard, DE 10 2008 061 330 A1 discloses a device for cutting individual pieces from a cheese band, which is initially cut into longitudinal strips and is then fed by means of a conveyor belt to a transverse cutting device. This cuts the longitudinal strips into individual pieces during the continuous motion, wherein the transverse cutting knife is moved back to the initial position after every cut.
Whereas the transverse cutting of such a flat band can be carried out in a very easily implemented, short “chopping motion”, the transverse cutting of a raised band, for example, a stack of a plurality of cheese bands lying on top of one another, requires a more complex motion sequence since the transverse cutting knife must be guided exactly perpendicularly to the movement of the band for a relatively long time during the entire cutting motion. In addition, it is highly desirable to not be limited to a single cut, but rather to have the option of cutting the bands in various lengths, for example.
In order to be capable of carrying out this type of complex cutting motions in a flexible manner, devices are used that utilize separate drives for the movement along each axis. Drives that are separated in this manner make a freely parameterizable and exact cutting sequence possible. In addition, such efficient transverse cutting devices can be used to cut endless cheese bands into individual stacks having any length, wherein no changeover times are required to change the guidance of the cut.
Known transverse cutting devices of the type used in this technical field have a knife holder, which is held on a slide guided by means of a cross guide. Such a cross guide is a system with two axis, comprising two linear guiding systems each having one axis, whereby the cross guide enables a movement of an object in two directions usually with an offset of 90° within a plane. In the known transverse cutting devices the slide is pneumatically driven along the transverse cutting direction (Z-axis). On the other hand, the drive along the conveyance direction (X-axis) utilizes a servomotor, i.e., an electric motor, which is held on a base plate in a stationary manner, in which the angular position of the motor shaft as well as the speed of rotation and the acceleration can be controlled by means of a sensor system. With this drive, the X-axis of the transverse cutting direction is synchronized with exact positioning, according to the “flying saw” principle, with the endless cheese band that is moving in the transport direction, wherein the knife cuts along the Z-axis in this synchronized movement.
A problem associated with the known devices, however, is that, during the pneumatically driven cutting in the Z-direction, there is no information available on the actual position of the knife and thus there is no position feedback at all during the course of cutting. In addition, the increasing requirements on a greater cutting depth and speed exceed the performance limit of these systems that can be achieved such that the process is reliable. Another disadvantage of the pneumatic Z-drive is the high energy loss in the end positions of the knife.
Although some of the aforementioned problems can be avoided with a second servomotor that drives the movement in the Z-direction, this concept is not feasible for most applications insofar as the second servomotor is mounted on the slide that is moved in the Z-direction and negatively affects the motion sequence and, therefore, the energy consumption, via its own weight. For example, the dimensions of the first servomotor would have to be increased accordingly.
A gantry drive, which is known from mechanical engineering, is another drive that could be considered, in principle, for such a compound table. In this movement system, a geometrical axis of the compound table is moved by means of two separate feed motors, which are driven in an angularly synchronous manner by means of converter control. A movement in the horizontal direction is generated when the two drives are moved in an angularly synchronous manner, i.e., with the same direction of rotation and at the same speed, whereas a movement in the vertical direction is generated when the two drives are moved in opposite directions of rotation and at different speeds. Any trajectory and coordinates in the movement area can be obtained by means of the interplay between the two drive motors. Such a gantry drive is slow and has limited dynamics, however, due primarily to its relatively large mass that must be moved. For this reason, the gantry drive has not been used so far in the guidance of tools in repetitive production processes, but rather were used only for systems that can be adjusted individually, such as patient beds in therapy and diagnostic devices, for example.
The problem addressed by the present invention is therefore that of creating a method for guiding a tool, in particular a transverse cutting knife, which acts on an object, in particular a moving product, in a repetitive motion, can be carried out with simple technical means, and permits rapid, flexible, and precise handling of the tool with low energy consumption and great dynamics. Another problem addressed by the invention is that of creating an easy-to-handle device for carrying out the method.